Recently several clinical reports have described birth defects in offspring of human alcoholic mothers. This pattern of craniofacial, limb and cardiac abnormalities, together with developmental delay, growth deficiency and mental retardation, has been named "fetal alcohol syndrome". In previous studies we have developed a Beagle model of the fetal alcohol syndrome by giving by gastric intubation a five-dose sequence of ethanol to pregnant Beagles throughout their gestation period of 9 weeks and studied the effects of this in utero exposure to alcohol on their offspring. In these experiments a "threshold dose" of ethanol has been determined that will reduce fetal development, induce abortion, cause stillbirth, decrease the size (as compared with controls) of liveborn pups, produce various structural abnormalilites and birth defects, and result in an increased incidence of early mortality of liveborn progeny. The continuation of this wok will be concerned with the administration of the threshold dose at various and short segments (only) of gestation in different groups of animals in an attempt to determine when during pregnancy such changes in fetal development are at high risk, and conversely, if there are periods during gestation when these effects are less likely to occur.